Many changes
Got some sample data out
Adds WEKA-like Instances and Attributes types
* Adds a float64-based Instances type representing features
* Adds FloatAttribute and CategoricalAttribute types
* Improves the CSV reader
* Overhauls KNN classification

Squashed commit of the following:

commit 7a78c4c5fe6ce7c43cd1b3e2f6090fc7bd25ecf8
Author: Richard Townsend <richard@sentimentron.co.uk>
Date:   Sat May 3 16:40:12 2014 +0100

    Think it is working..

commit 4669af674a736847e75485fc0d1cf09fe5a23615
Author: Richard Townsend <richard@sentimentron.co.uk>
Date:   Sat May 3 16:21:05 2014 +0100

    Very close to working..

commit 95735f09595c45156b42509b8108075618c5c31d
Author: Richard Townsend <richard@sentimentron.co.uk>
Date:   Sat May 3 15:11:23 2014 +0100

    Completed unit testing CSV reader

commit 1e69276f250770d1d692c7176032c6191b346f49
Author: Richard Townsend <richard@sentimentron.co.uk>
Date:   Sat May 3 14:56:18 2014 +0100

    Printing stuff